Idiom of the day :- Duty calls

Usage, examples and definition of the Idiom :-

I’d like to spend more time talking to you but duty calls, you know, and I have to hurry off to do my shopping,’ Helen said. Duty calls is another way of saying one must attend to one’s obligations. ‘Hey ! Duty calls ! Stop nodding off at your desks and get to work !’ the boss shouted.